1. Field of the Invention
The present invention relates generally to a door closer, preferably a top-mounted or overhead door closer. The door closer can include a closer shaft, which closer shaft can be actuated by a spring system in the closing direction. The door closer can also include a damping piston. The damping piston can, in effect, be connected to the closer shaft. An end of the closer shaft can extend out of the door closer housing. The end of the closer shaft can be coupled and connected to an actuator arm. The actuator arm can preferably be formed as a slide rail linkage. The slide rail linkage can be engaged in a guide rail by use of a slide. The slide can be located at the other end of the actuator arm. The closer shaft can include an eccentric cam plate. The cam profile of the eccentric cam plate corresponding to the opening direction can be pressurized by a spring assist element by use of at least one roller, and the cam profile of the eccentric cam plate corresponding to the closing direction can be pressurized by a damping piston by use of an additional roller. The roller of the damping piston and the roller of the spring assist element can be oriented substantially coaxially with the closer shaft.
In the door closer realized in accordance with the present invention, the damping piston and the spring assist element can preferably be manufactured as a single part. Placed inside a recess, between two rollers, there can be the eccentric cam plate. The eccentric cam plate can be mounted inside the door closer, and the projecting closer shaft can be connected to one end of the actuator arm. The other end of the actuator arm can interact with the sliding block of the slide rail.
2. Background Information
A known top-mounted door closer with a slide rail linkage is described in German Patent No. 40 38 720 C2, assigned to the assignee of the present invention. This sliding rail door closer is suitable for all types of installation, i.e. right or left stop on the strip or band side or on the side opposite the strip, both in a normal installation on the door panel and in an overhead installation on the door frame. An eccentric cam plate is used, the two eccentric cam plates of which are symmetrically constructed. As a result of the symmetrical cam profiles, the same torque curve is achieved in both directions of rotation. The eccentric cam plate is thereby fastened to a closer shaft. The closer shaft is mounted on one end in the lower portion of the housing, and is held in the other direction by an end-cap which is provided with a bearing. On one side, the eccentric cam plate thereby comes into contact with a roller which is inserted in the damping piston and on the other side with a roller which is inserted in the spring assist element. The damping piston and the spring assist element can execute movements independently of one another. For that purpose, pressure is applied to the damping piston by a compression spring and pressure is applied to the spring assist element by the compression spring of the spring actuator so that the two above-mentioned rollers come into contact on the inside against the eccentric cam disc. Inside the damping piston there is a non-return and pressure relief valve.
An additional door closer is described in German Patent No. 40 41 824 C1, also assigned to the assignee of the present invention, in which there are also a separate damping piston and a separate spring assist element. Each of the damping piston and the spring assist element is equipped with a roller. The damping piston and the spring assist element are located to the left and right in a housing so that the eccentric cam plate which is located on a shaft between them is engaged with these rollers. Pressure is applied to both the damping piston and the spring assist element by a compression spring toward the spring assist element. There are securing means to prevent a rotation of the spring assist element with respect to the damping piston. The function of the door closer is not in the least adversely affected by the presence of securing means in the form of pins, because even then, the damping piston and the spring assist element can operate completely separately from one another. The securing means can thereby be anchored, for example, on one end in the spring assist element and on the other end can be inserted without friction in blind holes on the opposite side inside the damping piston. The securing rods thereby run horizontally in relation to the vertical axis of the door closer shaft. If the damping piston and the spring assist element have a tendency to rotate with respect to one another, this rotation can be securely prevented by the securing means, because the rotational movement is prevented by the contact against the eccentric cam plate.